First of all sorry if this has been asked before, I could find "similiar" questions which seem to be harder but not quite this specific question.
You are given P white balls and Q black balls, how many ways can you put them into N different boxes?
My idea was to put first the P white balls into the N different boxes which can be done in $\binom{P+N-1}{P}$ ways (right?) then for each of these you do the same with the black balls so overall the answer is $\binom{P+N-1}{P}\binom{Q+N-1}{Q}$
Is this correct? If so is there a way to do it so you get a nicer form?